Grinding machine, especially for grinding spectacle glasses



1961 A. K. SEIRIG ElAL GRINDING M AC HINE ESPECIALLY FOR GRINDING SPECTACLE GLASSES 8 Sheets-Sheet 1 Filed Feb. 5, 1959 N w I Feb. 7, 1961 A. K. SEIRIG ETAL 2,970,409

GRINDING MACHINE, ESPECIALLY FOR GRINDING SPECTACLE GLASSES Filed Feb. 5, 1959 8 Sheets-Sheet 2 Hans-Toag/im Srruack Feb. 7, 1961 A. K. SEIRIG ETAL GRINDING MACHINE, ESPECIALLY FOR GRINDING SPECTACLE GLASSES 8 Sheets-Sheet 3 Filed Feb. 5, 1959 w n m m W i I e .w% R. mm mm n c mm mm N 9m 7m. P hi Q. wm mm mm mm mm m Q r s. 0 In! Z w 3 1 mw 4 mm 1 I r mm il..\ & NM Q R b a o mm mm 3 mm y B wq 3 Q m B 3 m 5 m m ll u l1 l |W|I um AH /|l l 3 mm m m m \\}./\.L J N Feb. 7, 1961 A. K. SEIRIG ETAL 2,970,409

GRINDING MACHINE, ESPECIALLY FOR GRINDING SPECTACLE GLASSES Filed Feb. 5, 1959 8 Sheets-Sheet 4 I N a m Feb. 7, 1961 A. K. SEIRIG ETAL 2,970,409

' GRINDING MACHINE, ESPECIALLY FOR GRINDING SPECTACLE GLASSES Filed Feb. 5, 1959 8 Sheets-Sheet 5 INVENTORS 0 S 2 fr)- qhx- 0 any, fi'unck Feb. 7, .1961 A. K. SElRl'G ETAL 2,970,409

GRINDING MACHINE, ESPECIALLY FOR GRINDING SPECTACLE GLASSES Filed Feb. 5, 1959 8 Sheets-Sheet 6 Fig. 9

Feb. 7, 1961 A. K. SEIRIG ET AL 2,970,409

GRINDING MACHINE, ESPECIALLY FOR GRINDING SPECTACLE GLASSES Filed Feb. 5, 1959 s Sheets-Sheet 7 INVENTOR.$

" 7 Se ,vv'

IQ I IJ s/Xunek Feb. 7, 1961 K. SEIRIG ETAL 8 Sheets-Sheet 8 Filed Feb, 5, 1959 INVENTOKS S 9 177' /ra "ck Q5 .H. a

jI nij tam GRINDING MACHINE, ESPECIALLY FOR GRIND- ING SPECTACLE GLASSES Alfred K. Seirig, Dusseldorf, and Hans-Joachim Strunck, Koln, Germany, assignors to Wernicke & Co. K.G., Dusseldorf-Eller, Germany The present invention relates to a grinding machine, particularly for grinding spectacle glasses. After spectacle glasses have been shaped in conformity with the approximate shape of the spectacle frame portions receiving said glasses, they are first pre-ground by a diamond disc and, thereupon, by means of a diamond disc, are given the final shape for fitting into the respective spectacle frame portions, said diamond disc carrying out a flat chamfer grinding or a pointed chamfer grinding.

Heretofore, the grinding of spectacle glasses was carried out in separate working operations on a diamond disc and a ceramic disc.

It is an object of the present invention to provide a grinding machine, especially for grinding spectacle glasses, which will considerably simplify the grinding operations heretofore carried out in the manner mentioned above.

It is also an object of this invention to provide a grinding machine, especially for grinding spectacle glasses, which will make it possible in a continuous op eration to effect the pre-grinding and finish-grinding.

It is a further object of this invention to provide a grinding machine, especially for grinding spectacle glasses, which will make it possible without a pre-grinding on the diamond disc to grind spectacle glasses directly on the diamond disc in a groove thereof.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

Fig. 1 is a perspective view of a work piece carrier of a grinding machine according to the present invention.

Fig. 2 is a front view partly in section of the work piece carrier of Fig. 1 with the grinding discs.

Fig. 3 represents a horizontal section taken along the line IIIIII of Fig. 2.

Fig. 4 is a perspective view of the control shaft with individual parts arranged therebelow.

Figs. 5 to illustrate details of the control mechanisms.

Figs. 11 to 13 show various positions of the control member for lifting off the spectacle glass held by the work piece carrier. 1

Figs. 14 and illustrate the adjusting distance of the spectacle glass during the transfer from the diamond disc to the ceramic disc.

Figs. 16 to 18 illustrate in different sections the tilting device for the work piece carrier.

GENERAL ARRANGEMENT The grinding arrangement according to the present invention is characterized primarily by the provision of a plurality of parallel grinding discs of which one disc is a diamond disc while the other is a ceramic disc. The grinding arrangement according to the present invention is further characterized by a control mechanism for lowering the work piece upon the grinding discs and/or lifting the'work pie'ceoff the same, said control mechaa p 2,970,409 l atented Feh- 1961 STRUCTURAL ARRANGEMENT Referring now to the drawings in detail, the arrangement according to the present invention comprises a work piece carrier 1; including a housing 2 which is tiltable about a stud or pivot 3a. as to height on pivot 3a by means of a set screw 3. The front portion of the work piece carrier is formed by a further housing portion 4 which is tiltable relative to housing 2 about a shaft 5 (Fig. 3) in such a manner that housing portion 4 can be tilted upwardly and downwardly in the direction toward the grinding discs 6 and 7 and away therefrom in conformity with the arrow A (Fig. 2). The tiltable housing portion 4 through which extends shaft 5 has at the right side thereof (with regard to Fig. 1) a clutch disc 8 which is connected to a shaft 9 which in its turn exceeds through the hollow shaft 5. Mounted on shaft 5 by means of a ball bearing 10 is a driving wheel 11 (Fig. 3) which by means of a V-belt 12 is driven byna motor (not shown) arranged in housing 2. The left end of shaft 9 (with regard to Fig. 3) which protrudes from hollow shaft 5 has connected thereto a worm wheel l3'm eshing with a worm wheel 14 connected to a shaft 15. Shaft 15 is journalled in a bearing member 17 which is tiltable about a shaft 16 and from which end 15a ofshaft 15 protrudes. Shaft 15 has a further worm wheel 18 mounted thereon which is adapted to be engaged by a worm wheel 20 connected toa shaft 19. The front end 15a of shaft 15 is arranged in a flattened portion 21 of an adjusting shaft 22 which latter is under the influence of a spring 23 and carries a'knurled head 24 with a stop or halting pin.

Parallel to shaft 9 and hollow shaft 5 there is arranged a shaft 19 carrying knurled heads 25 and having its front end journalled in a support 26 for holding the spec: tacle glass. The spectacle glass holder 26 is provided with an annular groove 27 engaged by fork portions 28 of a release mechanism 29 (Fig. 1). Spectacle glass holder-26 is provided with a flange 30 against which rests one end of a spring 31 the other end of which engages worm wheel 20 (Fig. 3). As will be evident from Fig. 3, spring 31 urges spectacle glass holder 26 toward. the right with regard to Fig. 3. Spectacle glass holder 26 is'furthermore provided with a slot 32 engaged by a follower pin 33'of shaft 19. If release mechanism 29 is turned in the direction of the arrow B (Fig. 1), the fork portion 28 moves the spectacle glass holder 26 against the thrust of spring 31 toward the left whereby a gap will be created between spectacle glass holder 26 and spectacle glass holder 34 for insertion of the spectacle glass: When releasing the release mechanism 29, spring 31 presses the spectacle glass holder 26 toward the right into its clamping position in which the spectacle glass will be held between the holders 26 and 34.

In housing portion 4 and parallel to shafts 9 and 19 there is journalled a control shaft 37 adapted to be driven throughthe intervention of gears 35, 36 (Fig. 3). At about the level of drive wheel 11, control shaft 37 carries a gear 38 keyed thereto and meshing with a gear 39 which is fixedly mounted on a shaft 40 of spectacle glass holder34. Shaft 4t has mounted thereon a' further gear 41'meshing with a gear'42 which by means of the bushing 43 is freely rotatably mounted on shaft 37. Bushing 43 Housing 2 is adjustable is provided with a cam 44, whereas control shaft 37 has mounted thereon a cam 45 fixedly connected thereto. That portion of shaft 40 which protrudes from the housmg portion 4 has mounted thereon a templet 46 which is held on shaft 40 by any convenient means. That portion of control shaft 37 which protrudes from the housing portion 4 has mounted thereon a control cam 47 (Figs. 1 and 3) and a tilting lever 48 with a nose 49, said lever with its nose being freely tiltable about control shaft 37. The said protruding portion of control shaft 37 has furthermore mounted thereon a control disc 50 with a thinner section 51 and a thicker section 52, and also carries a shift wheel 53 with a shift pin 54. The elements 47, 50 and 53 are fixedly connected to control shaft 37.

If clutch disc 8 with shaft 9 is by means of a device described further below adjusted in the direction of the arrow C (Fig. 3) toward the left against the thrust of spring 55, clutch disc 8 will be coupled to drive wheel 11. The rotary movement thus imparted upon shaft 9 is conveyed through worm wheels 13, 14 and shaft 15 to worm wheels 18, and thus to shaft 19 when the two last mentioned worm wheels mesh with each other. These worm wheels mesh with each other when end 15a of shaft 15 is located in the flattened portion 21. By rotating shaft 22, the bearing portion 17 acted upon by spring 56 will be turned about its pivot 16 in such a way that the two worm wheels 18 and 20 will disengage each other. By means of shaft 19, spectacle glass holder 26 will be turned while shaft 37 will be turned through the intervention of gears and 36. Gears 38, 39 bring about a rotation of shaft 40 and thus a synchronous rotation of spectacle glass holder 34 and spectacle glass holder 26. At the same time, cams and 47 as well as control disc 50 and control wheel 53 will be rotated by control shaft 37. Also cam 44 will be rotated, but in this instance, the ratio between the rotations of cam 44 and cam 45 will be 2523.5. By selecting transmission ratios different therefrom between gears 41 and 42, the said ratio of 2.5 :3.5 can be changed. The ratio of the speed of rotation of control shaft 37 to the speed of rotation of the spectacle glass holders 26, 34 may be selected accordmg to the speed of rotation which the spectacle glass is supposed to have during the grinding operation. The ratio of the speed of rotation of control shaft 37 to the speed of rotation of the spectacle glass holders 26, 34 may preferably be 113.5.

Laterally of the tiltable housing portion 2 and connected with the latter is a frame 57 of box-shaped contour. Rotatably journalled in said frame 57 by means of studs 58, 59 is a further tiltable frame 60 (Fig. 5) which is acted upon by a spring.61 resting against frame 57. Tlltable frame 60 carries a girder 62 with a guiding member 63 in which a control slide 64 is movable upwardly and downwardly. Girder 62 has an extension formed by a rod 65 on which a slidable beam 66 is displaceable in the direction of the arrow D. Tiltable frame 60 is furthermore provided with a strut 67 having mounted thereon a second rod 68 which forms the second bearing for the beam 66. Beam 66 carries a cam 69 and a rod 70. flame 44 and 45 of control shaft 37 will engage cam 69 1n conformity with the desired left or right extreme position of the slidable beam 66 on their guiding rods 65, 68.

In guiding member 63 there is journalled the front end of a control bar 71 whichis displaceable in the direction of the arrow E (Fig. 5). Control bar 71 carries a tilting lever 73 acted upon by a spring 72 and furthermore carriesa yoke 74 with a tiltable flap 75 which latter is urged nto inwardly tilted position by aleaf spring 76 as shown in Fig. 7. When beam 66 is displaced in the direction toward control bar 71, rod presses flap against the thrust of spring 76 into the position shown in Fig. 7, in which the set screw 77 will be located below the tilting lever 73, whereby lever 73 willbe held in its upright position when cam 47 of control shaft 37 abuts, inclined edge 73a.

The rear end of tilting frame 60 is provided with a second arm 78 carrying a vertically upwardly directed arm 79 with a pressure piece 80. That end 81 of pressure piece which faces clutch disc 8 acts upon the end face 9:: of shaft 9 when frame 60is turned about its studs 58, 59. By this turning or tilting movement, clutch disc 8 is brought into engagement with drive wheel 11-. Ann 78 is provided with a cut-out 82 (Fig. 6) in which slides control bar 71 and in any convenient manner, for instance by screws, is held in said cut-out. Frame 60 also carries a shaft 83 parallel to arm 78. Rotatably mounted on shaft 83 is a latch member 84. This latch member 84 is provided with an arm 85 and carries an angular member 86 which may rest behind the rear end face edge 87 of control bar 71 and also, as shown in Fig. 5, on the flattened end 88 of control bar 71. Inserted in latch member 84 are two studs 89, 90 (Fig. 6). Of these studs, stud 39 is intended to hold angular member 86 at its level when it is located behind end face 87 of control bar 71, whereas stud 90 supports one end of a spring 91 the other end of which is fastened to a stud 92 (Fig. 5) of a block 93 connected to control bar 71. By means of spring 91, control bar 71 is pulled toward the left with regard to Fig. 5, whereas latch member 84 is held in the direction of the arrow F in Fig. 6.

Within the range of control slide 64, control bar 71 (Figs. 5, 11 and 13) is provided with extensions 94 having a straight upper edge 94a, an inclined edge 94]), and a straight edge 94c. Control slide 64 is provided with corresponding extensions 95 (Figs. 5, 11 and 13) with a straight upper edge 95a, an inclined surface 95b corresponding to the inclined edge 94b, and with a straight edge 95c.

As will be seen from Fig. 8, on the horizontal portion of the box-shaped frame 57 there is mounted a slide 96 displaceable in the direction of the arrow G. Two guiding studs not shown in the drawing extend through oblong bores 97 for guiding and holding the slide. The rear end of slide 96 is provided with a transverse arm 98 adapted to abut arm 85 of the latch member 84. The front half of slide 96 is provided with a follower cam 99 having a cam surface 99a against which pin 54 of wheel 53 abuts and adjusts slide 96 which latter is held in its left hand position with regard to Fig. 8 by a spring 100. The central portion of slide 96 is provided with a support 101 receiving a set screw 102 which abuts against one end of a displaceable core wire 103 of a Bowden wire 104 when slide 96 is moved toward the right with regard to Fig. 8.

' The Bowden wire 104 is connected to frame 57 by means of that end which faces the support 101.

Within frame 57 and parallel to the tilting frame 60 and the control rod 71, there is journalled a coupling shaft 105 (Fig. 9) which is displaceable in the direction of the double arrow H and is rotatable. Flxedly mounted on shaft 195 is a clutch block 106 the bottom side of which is provided with two longitudinal cut-outs 107 and 108. The upper part of clutch block 106 carries a fork-shaped portion 109. Tiltably mounted on shaft 105 and tiltable relative thereto is a tilting fork 110 the legs 110a of which are provided with pins 111 adapted to engage the longitudinal cut-outs 107 and 108. The central portion 1101: of the tilting fork carries a stud 112 with a ball head 113. Also fixedly con-, nected to coupling shaft 105 is a shifter block 114. The lower portion of shifter block 114 is fork-shaped while the upper portion carries a shifter stud 115. Through the lower fork-shaped portion of shifter block 114 extends a shifter shaft 116 (Fig. 9) carrying an eccentric 117 and journalled in the tilting frame 60 and supporting arm 118 (Fig. 6a). The arm 119 is connected to a transverse arm 78. The front portion of arm 118 is provided with resting notches 119. Shaft 116 carries a transverse pin for engagement with the resting notches 119. A spring 120 is arranged between arm 118 and a flange 120a of shaft 116, said spring urging shaft 116 to move U in the direction of the arrow 1. In this way, the transverse pin is held in the resting notches 119, and shaft 116 is secured against an undesired turning. That end of shaft 116 which protrudes from-the supporting arm 118 carries a cam disc 121 which cooperates with a set screw 122 (Fig. arranged in block 93 of control rod 71.

Above tilting fork 110 and clutch block 106, the box-shaped frame 58 is provided with a T-shaped cutout 123. Laterally of this cut-out, frame 57 is provided with holding studs 124, 125 which prevent a lateral displacement of shifter fork 110 when shaft 105 is displaced in the direction of the arrow H. The T-shaped cut-out 123 is so designed that its wide portion 123a will permit a. tilting of the fork-shaped member 109, whereas the smaller portion 123b receives the forkshaped member in such a way that the clutch block 106 cannot tilt any longer and thereby will prevent shaft 105 from turning. Behind the cut-out 123, the cover plate of box-shaped frame 57 has a further T-shaped cut-out 126 engaged by stud 115 of shifter block 114; when stud 115 engages the smaller section 126a, a titing of the shifter block 114 and thereby a turning of the coupling shaft 105 will be prevented, whereas when stud 115 engages the wider portion 126b, a tilting of stud 115 and thus a turning of coupling shaft 105 will be possible.

At the level of the manually operable lever 48 (Fig. 4) and its nose 49, the upper portion of box-shaped frame 57 carries a limit jaw 127 (Fig. When the tiltable work piece carrier member 2 by movement of the two cams 44 and 45 against the limit cam 69 of the slidable beam 66 is tilted upwardly, nose 49 will move into the position shown in Fig. 10, whereby the work p'ece carrier member 2 will be held in lifting position. This lifting is effected at the end of the entire grinding operation, whereas during the grinding operation nose 49 engages the inclined surface 127a, and manually ope'rable lever 48 occupies a position inclined approximately 45 with regard to the surface of the frame 57.

Below frame 57 the lower portion of the machine has arranged the return adjusting device and also the tilting device which is generally designated with the reference numeral 128 (Fig. 2). The said return adjusting mechanism is engaged by the ball head 113 of the tiltable fork 119. The said return adjusting mechanism is formed by two scissor-like members 129 and 130 (Fig. 16) of which member 1319 is provided with a bushing 131 tiltable about a bearing stud 132 which latter has its lower portion connected to the lower portion of the machine. Bushing 131 is surrounded by a further bushing 133 of the scissor-like member 129 so that the bushing 131 is tiltable relative to stud 132 and bushing 133 is tiltable relative to bushing 131. The scissor-l ke member 139 is tiltable between two studs 134 and 135 of a transverse beam 136 and has its front portion provided with a clamping member 137. Opposite said clamping member 137 and arranged at the same level is a jaw 138 which is carried by a threaded bolt 139. Boit 139 extends through the front wall of the lower portion of the machine and is adapted to be screwed in and out in the direction of the arrow K (Fig. 17). By turning threaded belt 139, jaw 138 is moved parallel to itself and is pressed either against clamping member 137 or is moved away therefrom, whereby the member 130 will be held in its position or will be freely tiltable between studs 134 and 135. Member 130 is provided with an abutment 14$ cooperating with a stud141 of the upper member 129. Member 129 may be tiited into the dot-dash position shown in Fig. 17, whereas a return tilting movement of member 129 with regard to member 130 will be possible only until stud 141 abuts the abutment 144 The member 129 supports a box comprising a bottom piece '142 and two lateral plates 143 and 144 while the ball head 113 extends between plates 1'43 and 144'. At that end 129a of the member 129 which faces the bushings 131 and 133, member 129 carries a pivot 145 having tiltably linked thereto an arm, 146. This arm is acted upon by a spring 147 (Figs. 16 and 17) having one end connected to a pin 148 fixed t0 the side plate 144. Side plate 144 carries an angular member 149 threadedly engaged by a threaded member 150 for receiving the Bowden wire 104. The core 103 of Bowden wire 104 has its end face resting against a portion 151 of tilting arm 146. A drum 153 is connected to shaft 131 by means of two screws 152. Arranged in the interior of drum 153 is a torsion spr'ng 154 one end of which is connected to bushing 133 by means of a pin 155, whereas the other end of said torsion spring 154 is connected to the central portion 153a of drum 153 by means of a pin 156. Extending around the outside of the central portion 153a is a brake band 157 one end of which is connected to stud 145, whereas the other end of said brake band is connected to a holding member 159 by means of a set screw 158.

When the lower scissor-like member 130 is by means of jaw 138 clamped fast in a certain position between studs 134 and 135, and when the upper scissor-like memher 129 is tilted relative to the lower member 130, which tilting movement has to be effected against the thrust of brake band 158 tensioned by spring 147, the tersion spring 154 will be tensioned. When, by means of core 103, the tilting arm 146 is tilted in the direction of the arrow L (Fig. 17), the brake band 157 will be disengaged and member 129 will be turned back by torson spring 154 until stud 141 abuts the abutment 140 of the lower member 130 which latter, as described above, is held by jaw 138. During this return or reverse tilting movement of member 129 by means of torsion spring 154, the ball head between plates 143 and 144 together with its stern 112 will likewise be moved whereby the work piece carrier part 4 will be tilted, for instance, from the diamond disc to the level of the nut of the ceramic disc or to the level of the flat portion of the ceramic disc.

In order, when tilting downwardly the work piece carrier member 4, to avoid that the spectacle glass to be ground hits one of the grinding discs too strongly, the guiding member 63 (Fig. 4) has at the level of the transverse beam 62 provided thereon an oil or spring cylinder 160 from which protrudes a piston 161. A pin 162 on the control slide 64 cooperates with piston 161.

There will now be described the operation of the machine for each possibility of adjustment.

A. Grinding of the spectacle glass in simple pointed chamfer grind 0r diamond pre-grind In order to grind the spectacle glass, without a pregrind on the diamond disc, but exclusively in groove 7a of the ceramic disc 7, the beam 66 is manually moved into the position shown in Fig. 5. Furthermore, the adjusting lever 163 connected to shaft 116 is moved into its Fig. 5 position. The manually operable lever 48 with its nose 49 is moved into a position in which nose 49 engages the inclined surface 127a (Fig. 10). Control shaft 37 is manually rotated to such an extent that cam 44, now located above the cam 69, abuts cam 69 (Fig. 2). This adjustment may be effected by lifting the bearing member 17 (Fig. 3) by means of shaft 22 in such a way that the worm wheels 18, 20 will disengage each other, and by rotation of shaft 19, control shaft 37 will be turned without turning shafts 9 and 15. The front end of control rod 71 will then occupy the position shown in Fig. 11 in which the flat portions 941; of cam 94 engage control slide 64, whereas the flat portions 951; of the control slide engage control rod 71. In this position, the control, slide occupies its lowest position in grinding member 63. When the spectacle glass in groove 7a of the ceramic disc has been ground off sufliciently, templet 46 will rest on the said control slide 64 so that the contour of the spectacle glass will correspond to the 8. As a result thereof, shaft 9 will be coupled to drive wheel 11 and will be rotated through the intervention of shafts 15 and 19 of spectacle glass supporting member 26 and through the intervention of control shaft 37 of spectacle glass supporting member 34. If the contour of the spectacle glass is in excess of that of the templet, the templet will be lifted off from the control slide 64, and clutch disc 8 will disengage drive wheel 11. As a result thereof, a rotation of spectacle supporting mem bers 26, 34 will not be effected until again the desired grind has been effected and the templet will rest upon control slide 64. Due to the transmission ratio between shafts 19 and 40 on one hand and bushing 43 on the other handwhichratio may, for instance, be 2.5 :1- cam 44 will after 2 /2 revolutions of the spectacle glass engage cam 69 of member 66 and thereby will raise the work piece carrier member 4 which is tiltable about the hollow shaft 5. Nose 49 will due to the weight of the hand lever 48 move onto the upper edge of earn 127 into the position shown in Fig. 10. As a result thereof, work piece carrier member 4 remains in raised position and the grinding operation is completed. A further ro- .tation of the spectacle glass supporting members 26, 34 is not possible any longer because templet 46 does not any longer rest upon control slide 64, and clutch disc 8 is not any longer brought into connection with drive shaft 11 by the tilting frame and the members 80, 81. During the rotation of control shaft 37, cam 47 has passed by the tiltable pawl 73 without adjusting the same and thereby control rod 71. Pawl 73 is adapted to yield against the thrust of spring 72 because, as illustrated in Fig. 5, member 75 (Fig. 7) is tilted outwardly due to the leaf spring 76 so that set screw 77 does not catch below the tiltable pawl 73.

Due to the fact that control rod 71 does not move, the blocking angle 84 remains in its position on the fiat portion 88 of control rod 71 when slide 96 with its transverse part 98 abuts arm 85. Slide 96 (Fig. 4) is displaced by stud 54 of wheel 53. Due to the displacement of slide 96, screw 102 acts upon core 103 of the Bowden wire 104. However, the two scissor-like members 129 and 130 at the end of the Bowdenwire will not become effective. When grinding the spectaclerglass in the chamfer groove of the ceramic disc, it is irrevalent whether the lower scissor-like member 130 will or will not be clamped fast by jaw 138 (Fig. 17). Also with this grinding type, the adjustment of the scissor-like member 129 relative to the member 130 will be without importance. Due to the adjustment of shaft 116 by means of hand lever 163 (Fig. 9) into the position shown in Figs. and 9, clutch shaft 105 is by means of cam disc 117 and switch block 114 moved into Fig. 9 position. While tiltable fork 110 between the two studs 124 and 125 is prevented from moving in longitudinal direction, clutch shaft 105 will be moved into Fig. 9 position by cam disc 117 and switch block 114 unless it already occupies said Fig. 9 position. In this position, stud 111 of the tiltable fork does not engage clutch block 106 so that the tiltable fork is adapted to rotate freely on and relative to clutch shaft 105. Clutch shaft 105 itself cannot turn since pin 115 connected to shift block 114 engages the small portion 126a of the recess 126. The play necessary for the chamfer grind in groove 7a of the ceramic disc is obtained by the fact that then the work piece carrier members 2 and 4 are freely tiltable about stud 3a. While clutch shaft 105 through the box-shaped frame 57 is connected with said work piece carrier members 2 and ,4, and on the other hand ball stud 112 has its ball 113 arranged in the tilting device, fork-shaped member is adapted freely to rotate about clutch shaft 105 whereby it is also possible to tilt the work piece carrier members 2 and 4.

B. Pre-grinding of the spectacle glass by means of the diamond disc and post-grinding the spectacle glass in the chamfer groove of the ceramic disc For carrying out this grinding operation, the slidable beam 66 is displaced on bars 65, 68 in the direction to ward control bar 71 so that cam 69 will now be located at the level of cam 45. As a result thereof, flap 75 is by means of pin 70 and against the thrust of leaf spring 76 moved into its vertical position shown in Fig. 7 whereby set screw 77 catches below tiltable member 73 (Fig. 5) and locks the same against tilting movement.

Shaft 116 is by means of hand lever 163 turned in such a way that said hand lever will occupy the position N shown in Fig. 9 while the eccentric portion of cam disc 117 points toward the right and the eccentric portion of cam disc 121 points toward the left. The blocking angle 84 will be moved into a position behind end edge 87 of control rod 71. The lower scissor-like member will, while brake jaw 138 is engaged, due to a turning movement of work piece carrier members 2 and 4 about stud 3a, move into a position in which the spectacle glass will be held above the chamfer groove of the ceramic disc in spectacle glass holders 26, 34. Thereupon, brake jaw 138 is pressed against part 137 of the lower scissor-like member 130 whereby this scissor-like member is held stationary. The work piece carrier members 2 and 4 are then turned about stud 3a until the spectacle glass circumference will reach the level of the diamond disc. With this adjusting device, nose 49 rests upon cam 127, whereby work piece carrier member 2 will be tilted upwardly, and the spectacle glass will be able to rest on one of the grinding discs. By tilting the handle 48 upwardly, work piece carrier member 2 can be lowered at the start of the grinding operation, whereby the spectacle glass will first engage the diamond disc. During the adjustment of the work piece carriers 2 and 4 to such an extent that the spectacle glass circumference will be located above the diamond disc, the upper scissor-like member 129 will be moved into the dot-dash position of Fig. 17 while the effect of the brake band 157 will be overcome and simultaneously the torsion springs 154 will be tensioned. The starting portion of cam 45 at the beginning of the grinding operation will, similar to the exclusive grinding of the spectacle glass in the chamfer groove of the ceramic disc, be such that cam 45 will be located shortly behind the cam 69 when looking in the direction of rotation. Since the rear end edge 87 of control rod 71 engages the angular lever 84, control rod 71 will first be held in a position which is illustrated in full lines in Fig. 12. As a result thereof, slide 64 will occupy the position likewise shown in full lines in Fig. 12 so that the control slide will be held stationary relative to the control rod by means of the engaging inclined surfaces of the two parts. Similar to the grinding of the spectacle glass rim in the chamfer groove of the ceramic disc, templet 46 presses against slide 64 when the spectacle glass circumference has to be ground off to such .an extent that the spectacle glass does not rest any longer on the diamond disc, but templet 46 rests on slide 64. Due to the fact that templet 46 rests on slide 64, the tilting frame 60 turns about studs 58, 59, and clutch 8 is engaged with the drive wheel 11. With all grinding operations, it is thus possible to maintain the drive motor in continuous operation. No shifting of this motoris necessary. Due to the simultaneous turning of control shaft 37 with the spectacle glass holder shafts 19, 40, after one revolution of shafts 19, 40, i.e. a grinding off of the spectacle glass circumference by 360? on the diamond disc, cam 47 will engage the 'tiltabl'e latch 73 which latter, as described above, is held in rigid engagement with control rod or bar 71 by means of flap 75 and set screw 77. When cam 47 slides off along the inclined edge 73a of the tiltable latch 73, control rod 71 is moved forwardly into Fig. 13 position so that the straight edges 95a of control slide 64 will rest on the straight edges 94a of control rod 71. This brings about a raising of the templet 46 and thus a raising of the work piece carrier member 4 with its front portion, while the rear portion will be tilted with regard to the Work piece carrier member 2 about shaft 5. The spectacle glass will thus move over the distance designated with the letter O in Fig. 15. During the lifting of the front portion of the work piece carrier member 2 and thus during the lifting off of the spectacle glass from the diamond disc, pin 54 has engaged cam 99 of slide 96 whereby during a further rotation of control shaft 37 and cam 54, slide 96 will be pressed forwardly, i.e. toward the right with regard to Fig. 6. The rear transverse piece 98 (Fig. 8) of the slide 96 engages arm 85 of the angular lever 84 whereby the latter is lifted out of its position behind the end edge 87 of control bar 71. As a result thereof, control bar 71 is adapted in a manner to be described further below, in view of spring 91, to quickly move toward the rear, i.e. toward the left with regard to Fig. 5. During the forward movement of slide 96, set screw 102 will engage core 103 of Bowden wire 104. This core will then press against the holding member 151 of the tilting arm 146, whereby the latter is, against the thrust of spring 147, turned about pivot 145 in the direction of the arrow L (Fig. 17). As a result thereof, the band brake 157 is disengaged, and in view of the torsion spring 154, the upper scissor member 129 can rotate until its pivot 141 abuts the abutment block 140 of the lower scissor member 130. In this way, the upper scissor member has carried out a tilting movement which corresponds to the tilting movement of the work piece carrier members 2 and 4 and of the spectacle glass from the diamond disc to the level of groove 7a of the ceramic disc. The stroke of the spectacle glass during the tilting movement of the work piece carrier members 2 and 4 is designated with the letter P in Fig. 15. The tilting movement of the work piece carrier members 2, 4 is effected through the intervention of the ball head 113, the ball head stud 112, and the tiltable fork 110. Due to the position of the eccentric part of cam disc 117, which eccentric part at the selected adjustment points toward the right with regard to Fig. 9, the clutch shaft 105 has likewise been moved toward the right so that the right-hand pivot 111 of the tiltable fork 110 engages the right-hand recess 103 of the clutch block 106. In this way, the fork 110 with its pivot 112 is rigidly connected to shaft 105 which cannot turn as long as the thicker portion 52 of disc 50 engages the fork-shaped part 109 of clutch block 106. If, however, the thinner section 51 of disc 50 is located between the fork-shaped portion 109, shaft 105 will be able to turn within certain limits depending on the thickness of the section 51 with regard to the gap in the fork-shaped portion 109. During the grinding of the spectacle glass on the diamond disc, the spectacle glass has to be secured against lateral turning. To this end, the thicker portion 52 of disc 50 engages the forkshaped portion 109 whereby a turning of clutch shaft 105 is not possible and, consequently, the work piece carrier members 2 and 4 are secured against a tilting movement. During the tilting of the upper scissor member 129, the thicker portion 52 of disc 50 engages fork-shaped portion 109. When the spectacle glass has been tilted to the level of groove 7a, due to the turning of control shaft 37 and disc 50, the thinner portion 51 will engage the gapin the fork-shaped portion 109. At the same time, the control slide 64 is lowered into the position shown in Fig. 11. This is brought about by the fact that control .bar .71 springs back, i.e. moves toward the left with .regard to Fig. 5. The angle 84, as mentioned above, is raised dur- "ing this period. After it has been lowered, it engages the flat portion -88 of control bar 71. Control bar 71 can move back as far as canidisc 121 will permit. Since its eccentric portion is directed toward the leftwith regard to Fig. 5, control'bar 71 can return to its position which it will also occupy during the ordinary grinding of the spectacle glass in the chamfer groove of the ceramic disc. The stroke during the downward movement of the spectacle glass into the groove of the ceramic disc '7 is designated in Fig. 15 with the letter Q.

After the grinding operation has been completed, i.e. after for instance one revolution of the spectacle glass on the diamond disc, after the subsequent transfer into the groove of the ceramic disc, and after approximately two and one-half revolutions of the spectacle glass in this groove, cam 47 engages cam 69 whereby the work piece carrier member 4 is tilted about shaft 5 with regard to work piece carrier member 2. Nose 49, which up to that time had rested on the incline 127a, will then engage cam 127 (Fig. 10). As a result thereof, clutch member 8 does not any longer engage drive wheel 11. The grinding operation has thus been completed.

C.--Pre-grina'ing of the spectacle glass on the diamond disc and subsequent grinding 0 the glass on the flat portion of the ceramic disc With this grinding operation, in contrast to the grinding of the spectacle glass on the diamond disc and in the groove of the ceramic disc, it is decisive that during the grinding on the diamond disc as well as during the grinding on the flat portion of the ceramic disc, the spectacle glass will be secured against lateral displacement. The slidable member 66 is again displaced in the direction toward the control bar 71 whereby the tiltable latch 73 .is held in rigid connection with the control bar 71. Shaft 116 is by means of handle 163 turned in such a way that the handle occupies the position R shown in Fig. 9. In this position, the eccentric portion of cam disc 117 points toward the left, whereas the eccentric portion of cam disc 121 points toward the right. As a result thereof,

by means of block 114, clutch shaft is likewise moved toward the left so that the left-hand stud 111 of the tiltable fork engages the left recess 107 of clutch block 106. In this way, fork 110 is again rigidly connected to clutch shaft 105. Clutch shaft 105 cannot turn during the grinding on the diamond disc and on the ceramic disc because pin of switch block 114 which is firmly connected to clutch shaft 105 will rest in the narrow portion 126a of the recess 126. The work piece carrier members 2 and 4 are tilted to such an extent that the spectacle glass will occupy a position above the fiat portion of the ceramic disc. In this position, the two superimposed scissor members 129, 130 occupy a certain position. During this operation, the clamping jaw 138 is first disengaged. It will be engaged when the work piece carrier members 2, 4 with the spectacle glass will occupy the described position. vThereupon the work piece carrier members 2, 4 are tilted about pivot 3a in such a way that the spectacle glass will occupy a position above the diamond disc. In this position, the upper scissor member 129 will be tilted relative to the lower scissor member 130 against the-effect of the band brake 157 while tilting the torsion spring 154, The angular lever 84 will be located again behind the end edge 87 of control bar 71 whereby the latter will occupy the position shown in full lines in Fig. 12. When looking in the direction of rota.- tion, cam 45 is located shortly behind cam 69,. During the tilting of the hand lever 48 in such a way that nose 49 rests upon the inclined portion 127, templet 46 is and control shaft37 are actuated, and the spectacle glass is ground in conformity with the contour of templet 46. During the turning of the control shaft 37, cam 47 en gages the incline 73a of the rigidly held tiltable latch 73 whereby control bar 71 is moved forwardly, i.e. toward the right with regard to Fig. 5 and will occupy the position shown in Fig. 13. Furthermore, stud 54 engages cam 99 of slide 96 (Fig. 4) and adjusts the same again toward the right with regard to Fig. 8. The transverse member 9 8 then tilts angle 84 and acts upon core 103 of Bowden wire 104. When hand brake 157 is disengaged, the upper scissor member 129 due to torsion spring 154 springs back until pivot 141 engages block 140. During the lifting oil of the spectacle glass from the diamond disc, said glass has again performed the stroke in Fig. 15. During the tilting operation, the spectacle glass performs the stroke P plus S whereby it arrives at the level of the flat portion of the ceramic disc. A tilting movement of members 2 and 4 is thus not possible inasmuch as the tiltable fork 110 rests in the upper scissor member 129 which is held stationary by the brake through the intervention of stud 112. Furthermore, tiltable fork 110 is rigidly connected to shaft 105 which is prevented from turning by engagement of pin 115 with the narrow slot When the spectacle glass has reached the level of the ceramic disc, i.e. has performed a stroke P plus S, it will be lowered again upon the ceramic disc due to the fact that the control bar 71 moves back, i.e. toward the left. Inasmuch as the eccentric portion of cam disc 121 points toward the right with regard to Figs. 5 and 9, a return movement of control bar 71 is possible only into the position shown in dot-dash lines in Fig. 12. This means that slide 64 is lowered less than during the grinding of the spectacle glass in the chamfer groove of the ceramic disc. The downward movement of the spectacle glass upon the flat portion of the ceramic disc is indicated by the arrow T in Fig. 15. In Figs. 12 and 14, the difference in height of the various positions of slide 64 are indicated. The letter a designates the difference resulting from the difference in height between the upper edge of the diamond disc and the lowest point in groove 7a plus the oil-grind in the groove of the ceramic disc. The letter b designates the difference in height between the circumference of the diamond disc and the circumference of the ceramic disc plus the off-grind on the ceramic disc. After the spectacle glass has performed approximately one revolution on the diamond disc, and subsequently was transferred from the diamond disc to the flat portion of the ceramic disc and after it has performed approximately two and one-half revolutions on the ceramic disc, cam 45 engages cam 69 whereby the work piece carrier member 2 is tilted upwardly about shaft 6 with regard to the work piece carrier member 2. Nose 49 will then rest upon cam 127, and the grinding operation has been completed.

It is, of course, to be understood that the present invention is, by no means, limited to the particular construction shown in the drawings, but also comprises any modifications within the scope of the appended claims.

What we claim is:

1. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting voff or lowering the same onto the respective grinding disc therebelow, control means operatively connected to said control member for actuating the latter, and shifting means operatively connected to said work piece supporting'means and operable by said control means for from a position above one of said discs to a position above another one of said discs.

2. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, shiftable springloaded frame means, a reciprocable control member supported by said frame means and operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, control means operatively connected to said control member for actuating the latter, and shifting means operatively connected to said work piece supporting means and operable by said control means for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

3. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said disc, shiftable springloaded frame means, a reciprocable control member supported by said frame means and operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, a rotatable control shaft, a plurality of cams supported by said control shaft and respectively having different speeds of rotation, guiding means supported by said frame means, a transverse beam reciprocable on said guiding means, a cam member mounted on said'transverse beam, said transverse beam being movable toward said cams for bringing said cam member into cooperation with said cams to bring about actuation of said control member, and shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

4. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, a guiding frame, a reciprocable control member reciprocably guided in said frame and operable selectively to lift or to lower said supporting means for lifting a work piecethereon off or lowering the same onto the respective grinding discs therebelow, control means operatively connected to said control member for actuating the latter, and shifting means op eratively connected to said work piece supporting means and operable by said control means for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

.5. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, a guiding frame, a reciprocable control member reciprocably guided in said frame and operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said frame and provided with second inclined surfaces for engagement and cooperation with said first inclined surfaces, control means operatively connected to said control bar for actuating the latter, and shifting means opera-. tively connected to said work piece supporting means and operable by said control means for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

6. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, a supporting frame, work piece supporting means supported by said supporting frame for supporting the work piece to be ground, said frame being movable upwardly and downwardly to thereby move said Work piece supporting means from a level higher than said discs toward said discs and also being movable in '1 the opposite direction, said supporting frame also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocable control member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with said'first inclined surfaces, 21 shiftable pawl supported by said reciprocable bar, a control shaft journalled in said supporting frame, a control cam mounted on said control shaft for rotation therewith, said control-cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reciprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position into a locking position for locking said pawl to said reciprocable bar, and shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above work piece supporting means from a level higher than said discs toward said discs and also being movable in the opposite direction, said supporting frame also being shiftable about an axis and in a direction transverse to toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocable control. member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with saidfirst shaft for rotation therewith, said control cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reciprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position int-o a locking position for locking said pawl to said reciprocable bar, a two-arm resilient lever journalled in said auxiliary frame near one end of said reciprocable control bar, said two-arm lever being tiltable into a position in which one arm of said twoarm lever is located behind an end portion of said reciprocable control bar, and shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

8. In a grinding machine, especially for grinding spectacle, glasses: a plurality of rotatable substantially parallel grinding discs, a supporting frame, work piece supporting means supported by said supporting frame for supporting the work piece to be ground, said frame being movable upwardly and downwardly to thereby move said work piece supporting means from a level higher than said discs toward said discs and also being movable in the opposite direction, said supporting frame also being shiftable about an axis and in a direction transverse to the direction of movement of said supthe direction of movement of said sup-porting means porting means toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocablecontrol member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon off or lowering the same onto. the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with said first inclined surfaces, a shiftable pawl supported by said reciprocable bar, a control shaft journalled in said supporting frame, a control cam mounted on said control shaft for rotation therewith, said control cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reciprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position into a locking position for locking said pawl to said reciprocable bar, a manually operable shift rod turnably journalled in said auxiliary frame, cam means connected to said shift rod, adjustable means connected to said reciprocable control bar and engageable by said last mentioned cam means for actuating said control bar, and shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

'15 grinding discs, a supporting frame, work piece supporting means supported by said supporting frame for supporting the work piece to be ground, said frame being movable upwardly and downwardly to thereby move said work piece supporting means from a level higher than said discs toward said discs and also being movable in the opposite direction, said supporting frame also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocable control member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with said first inclined surfaces, a shiftable pawl supported by said reciprocable bar, a control shaft journalled in said supporting frame, a control cam mounted on said control shaft for rotation therewith, said control cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reciprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position into a locking position for locking said pawl to said reciprocable bar, a manually operable shift rod turnably journalled in said auxiliary frame, cam means connected to said shift rod, adjustable means connected to said reciprocable control bar and engageable by said last mentioned cam means for actuating said control bar, a coupling shift journalled in the supporting frame which has the auxiliary frame tiltably journalled therein, eccentric means connected to said shift rod for adjusting said coupling shaft in longitudinal direction thereof, and shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

10. A grinding machine according to claim 9, in which the supporting frame for said auxiliary frame has a portion provided with two T-shaped cutouts, and which includes a shifter block mounted on said coupling shaft and engaged by said eccentric means, a control pin connected to said shifter block and engaging one of said T-shaped cutouts.

11. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, a supporting frame, work piece supporting means supported by said supporting frame for supporting the work piece to be ground, said frame being movable upwardly and downwardly to thereby move said work piece supporting means from a level higher than said discs toward said discs and also being movable in the opposite direction, said supporting frame also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocable control member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with said first inclined surfaces, a shiftable ,pawl supported by said reciprocable bar, a control shaft journalled in said supporting frame, a control cam mounted on said control shaft for rotation therewith, said control cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reciprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position into a locking position for locking said pawl to said reciprocable bar, a manually operable shift rod turnably journalled in said auxiliary frame, cam means connected to said shift rod, adjustable means connected to said reciprocable control bar and engageable by said last mentioned cam means for actuating said control bar, a coupling shaft journalled in the supporting frame which has the auxiliary frame tiltably journalled therein, a clutch block connected to said coupling shaft and comprising a fork-shaped member, and'shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

12. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, a supporting frame, work piece supporting means supported by said supporting frame for supporting the work piece to be ground, said frame being movable upwardly and downwardly to thereby move said work piece supporting means from a level higher than said discs toward said discs and also being movable in the opposite direction, said supporting framealso being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocable control member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon ofi or lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, a reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with said first inclined surfaces, a shiftable pawl supported by said reciprocable bar, a control shaft journalled in said supporting frame, a control cam mounted on said control shaft for rotation therewith, said control cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reciprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position into a locking position for locking said pawl to said reciprocable bar, a manually operable shift rod turnably journalled in said auxiliary frame, cam means connected to said shift rod, adjustable means connected to said reciprocable control bar and engageable by said last mentioned cam means for actuating said control bar, a coupling shaft journalled in the supporting frame which has the auxiliary frame tiltably journalled therein, two spaced abutment pins connected to said supporting frame which has the auxiliary frame tiltably journalled therein, a shifter fork rotatably mounted on said coupling shaft, a clutch block connected to said coupling shaft near said shifter fork and adapted to be coupled thereto, and shifting means operatively connected to said work piece supporting means and operable by said control shaft for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

13. A grinding machine according to claim 12, in which the supporting frame for said auxiliary frame comprises a portion provided with T-shaped cutouts, and in which said clutch block is provided with a fork-shaped portion engaging one of said T-shaped cutouts.

14. ,In a grinding machine, especially for grinding spectacle" glasses a "plurality of rotatable.substantially parallel grinding discs, work piece supporting means for supporting the work piece-to be ground, said work piece supporting :means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, manually operable lever means supported by said work piece supporting means, a housing, cam means supported by said housing and engageable by said manually operable lever means for maintaining said work piece supporting means at a level higher than said discs, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, a reciprocable control member operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, control means operatively connected to said control member for actuating the latter, and shifting means operatively connected to said work piece supporting means and operable .by said control means for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

15. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, a supporting frame, work piece supporting means supported by said supporting frame for supporting the work piece to be ground, said frame being movable upwardly and downwardly to thereby move said work piece supporting means from a level higher than said discs toward said discs and also being movable in the opposite direction, said supporting frame also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, an auxiliary frame tiltably journalled in said supporting frame, guiding means supported by said auxiliary frame, a reciprocable control member reciprocably guided in said guiding means and operable selectively to lift or to lower said supporting frame for lifting a work piece thereon offer lowering the same onto the respective grinding disc therebelow, said control member being provided with first inclined surfaces and adjacent substantially horizontal supporting surfaces, 21 reciprocable control bar supported by said auxiliary frame and provided with second inclined surfaces for engagement and cooperation with said first inclined surfaces, a shiftable pawl supported by said reciprocable bar, a control shaft journalled in said supporting frame, a control cam mounted on said control shaft for rotation therewith, said control cam being operable to engage said shiftable pawl, resilient latching means for locking said shiftable pawl, an actuating member reeiprocably arranged on said auxiliary frame and operable to move said latching means from a normally open position into a locking position for locking said pawl to said reciprocable bar, a manually operable shift rod turnably journalled in said auxiliary frame, cam means connected to said shift rod, adjustable means connected to said reciprocable control bar and engageable by said last mentioned cam means for actuating said control bar, a coupling shaft journalled in the supporting frame which has the auxiliary frame tiltably journalled therein, two spaced abutment pins connected to said supporting frame which has the auxiliary frame tiltably journalled therein, a shifter fork rotatably mounted on said coupling shaft, a clutch block connected to said coupling shaft near said shifter fork and adapted to be coupled thereto, said supporting frame for the auxiliary frame comprising a portion provided with T-shaped cutouts, one of said cutouts being engaged by a fork-shaped portion of said clutch block, a control disc of different thickness extending between said fork-shaped portion of said clutch block, and shifting means operatively connected to said work piece supporting means and supporting means about said axis from aposition above one of said discs to a position above another one of said discs.

16. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, shiftable spring-loaded frame means, a reciprocable control member supported by said frame means and operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, a rotatable control shaft, a plurality of cams supported by said control shaft and respectively having different speeds of rotation, guiding means supported by said frame means, a transverse beam reciprocable on said guiding means, a cam member mounted on said transverse beam, said transverse beam being movable toward said cams for bringing said cam member into cooperation with said cams to bring about actuation of said control member, stud means connected to said control shaft, a reciprocable slide displaceable by said stud means and provided with abutment means, and shifting means operable by said abutment means for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs.

17. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, a reciprocable control member operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, control means operatively connected to said control member for actuating the latter, shifting means operatively connected to said work piece supporting means and operable by said control means for turning said work piece supporting means about said axis from a position above one of said discs to a position above another one of said discs, said shifting means comprising two scissor-like members, a brake band arranged for cooperation with said scissor-like members to hold the same in a respective desired position, and spring means for tilting said scissor-like members toward each other.

18. In a grinding machine, especially for grinding spectacle glasses: a plurality of rotatable substantially parallel grinding discs, work piece supporting means for supporting the work piece to be ground, said work piece supporting means being movable from a level higher than said discs toward said discs and also being movable in the opposite direction, said work piece supporting means also being shiftable about an axis and in a direction transverse to the direction of movement of said supporting means toward and away from said discs, a reciprocable control member operable selectively to lift or to lower said supporting means for lifting a work piece thereon off or lowering the same onto the respective grinding disc therebelow, control means operatively connected to said control member for actuating the latter,

shifting means operatively connected to said work piece supporting means and operable by said control means for wturning said work piece supporting means about said.

.axis from a position above one of said discs to a position above another one of said discs, said shifting means comprising a lower scissor-like member and also comber for actuating the same.

' 19. A grinding machine according to claim 18, in

20 which the upper scissor-like member is provided with a stud engaging the lower scissor-like member for actua tion of the latter in response to the tilting movement of said upper scissor-like member in one direction.

References Cited in the file of this patent" UNITED STATES PATENTS 1,619,358 Maynard Mar. 1, 1927 

